1. Field of the Invention
The present invention relates to a structure of connecting an optical waveguide part and a holding part of holding an optical input member such as an optical fiber, in which deviation of an insertion loss and an light amount is low with respect to cycles of thermal shock.
2. Related Art Statement
In the case that laser light is transmitted using an optical fiber and connected to an optical waveguide, a holding part of holding the optical fiber is usually connected to an optical waveguide part through an optical adhesive.
In the case that the optical adhesive is applied between end faces of the optical fiber and optical waveguide to form an adhesive layer, however, the adhesive layer is present in the optical path. Then, in the case that laser of a high output power is used as a light source, the generated heat may possibly deteriorate the adhesive.
Therefore, as a method for preventing the deterioration of the adhesive, it was proposed Patent document 1 (Japanese Patent Publication No. 2010-185,980A). According to the method, for example as shown in FIGS. 7 and 8, recesses 30 are formed in two regions of an optical waveguide substrate 18, and protrusions 31 are formed at both of right and left ends of the optical waveguide substrate 18 viewed from the optical waveguide by the recesses 30. Then, an end face 31a of each protrusion 31 is made an adhesive face, and they are adhered onto a substrate 2 of holding an optical fiber through an optical adhesive 12. At this time, the optical adhesive is not provided between the optical fiber and optical waveguide. The optical adhesive is thereby out of the optical path so that it is possible to prevent the deterioration of the adhesive.    Patent document 1: Japanese Patent Publication No. 2010-185,980A